1. Field of the Invention:
The invention relates to a running-in tool for effecting the setting of a subterranean well hanger or packer in which accidental setting of the slips during run-in is prevented by the incorporation of a positive locking mechanism in the hydraulic running tool which maintains the actuating mechanism for the slips in a positively locked position until fluid pressure is applied to a piston element incorporated in the running tool.
2. History of the Prior Art:
It is a common practice in the completion of subterranean wells to effect the hydraulic setting of a packer or hanger within the well casing by expansion of slips into engagement with the casing bore. As exemplified by the disclosure of the U.S. Pat. No. 4,393,931 to MUSE et al, it is common practice to provide in the hydraulic running tool, an annular piston, which is actuated by fluid pressure when the slips of the packer or hanger are disposed in the proper position within the well casing, to shift an actuating sleeve to release the slips into biting engagement with the casing wall. As disclosed in the aforesaid MUSE et al patent, premature release of the slips was prevented through the utilization of one or more shear screws which effected a rigid securement of the actuating piston to the body of the hydraulic running tool. This system of locking the piston has, however, proven unsatisfactory in numerous occasions due to the fact that the shear screws can be inadvertently sheared by impact received on the actuating mechanism for the slips as the hanger or packer is run into the well on the hydraulic running tool. There is, therefore, a definite need for a positive locking mechanism for effecting the securement of the slip actuating sleeve of a hanger, packer, or like device, in a position holding the slips in an inoperative position until the slips are properly positioned in the well.